1. Field of the Invention
The invention relates to a device for mechanical vibration decoupling with two bearing ends, onto which bodies for reciprocally decoupling vibrations can be joined or are joined and which are interconnected via a coupling structure with a variably adjustable stiffness.
2. Description of the Prior Art
If a body has to be borne with as little vibration as possible, for example for isolating a body against the vibrations predominating in the area surrounding the body, or to prevent the transmission of a stimulus from a vibrating body to the surrounding area, in a known manner a device for mechanical vibration decoupling, a bearing is used, which via a coupling structure has as little stiffness as possible. Passive bearings are devices for mechanical vibration decoupling, having a coupling structure which is predefined via an invariable stiffness, such as for example due to a spring or rubber element. The bearing stiffness of passive bearings has the particular disadvantage of excessive vibration on occurrence of the resonance frequency of the vibrating coupled system. Resonance maximum vibration amplitudes occur which lead to increased noise nuisance and considerable structural weakening of the bodies connected by the bearing. This disadvantage is countered by increasing the damping, whereby, however, the effect of vibration decoupling worsens at higher frequencies.
In contrast to this, active bearings provide a variation of the stiffness of the coupling structure arranged between the two bodies for decoupling vibrations. Active bearings usually have a coupling structure having a basic stiffness and a sensor for recording the current vibration status as well as an actuator influencing the stiffness of the coupling structure. As part of controlled force input provided by the actuator on the stiffness of the active bearing, the increase in vibration in the event of resonance can be reduced without permanently impairing the isolation effect at higher frequencies, as in the case of a passive bearing.
As an example of an active bearing, reference is made to U.S. Pat. No. 5,645,260 which discloses an active bearing unit for the isolating a payload relative to a vibrating substrate. The payload is fixed to the upper section of an S-shaped curved aluminium bracket which has a lower end securely fastened to the vibrating substrate. The aluminium bracket has both a horizontally and vertically orientated bracket section. Rat piezo actuators are applied along each bracket section. To dampen the vibration of the payload loaded by the aluminium bracket, a vibrating substrate is provided to which control signals are applied to horizontal and vertical flat piezo actuators through which the horizontal and vertical orientated bracket section experience corresponding dynamic stiffening for attenuating or completely preventing the transmission of vibration by the vibrating substrate to the payload.
DE 690 32 856 T2 describes a vibrating damping system providing for vibrations of very small amplitude being damped, particularly in a lower frequency range. In principle the vibration damping system comprises a vertical damping device and a horizontal damping device both with a stiffness of zero or almost zero. An essential part of the vertical damping device is a triple arm spring element, in the middle of which the load impinges. The stiffness of the spring elements is adjusted by force acting radially from outside on “arms” so that a net stiffness of almost zero is achieved. Load bearing devices are used to adjust the radial forces, which have two cantilever-like bending devices arranged between a middle section and two ends. The ends are firmly attached to the base by way of so-called spacer blocks.
EP 1 927 782 A1 discloses an active mass damper with a cantilever beam, which connects a mass damper with a fastening device. Arranged on at least one side of the cantilever beam is a piezoelectric actuator which bends the cantilever beam. This produces a force on the fastening structure which has a vibration damping effect.
DE 10 2005 043 429 A1 describes a device for vibration decoupling having a sensor-actuator unit for recording load-related vibration of a means and counteracts the vibration of the means. Sensors and/or actuators can comprise a transducing material, for example a piezoelectric material.
U.S. Pat. No. 3,185,428 describes a bearing allowing a translational movement in three spatial directions, but prevents rotation. The bearing comprises four parts that are moveable with regard to each other, namely a base and three frames nested one inside the other. The base is connected to any type of supporting structure. The load is arranged on the innermost frame. The frame can moved in all spatial directions, that is, in two horizontal directions and vertically without, however, being able to rotate about a vertical axis of rotation. The inner frames are each supported against the externally surrounding frame with a pair of leaf springs arranged on opposite frame sides, whereby the pair of leaf springs between the innermost and the second frame is offset by 90° with regard to the other pair of leaf springs. Each leaf spring is connected by one end to the frame on the inside and by the middle thereof to the frame on the outside. The outermost frame is connected to the basis via vertically arranged leaf springs.
AT 345 02 042 B discloses a spring set for the concentric, sprung guiding of oscillating moved components provided by spring elements which are aligned in parallel and are fixed against each other by spacing elements at their ends. The spring set comprises a pair of springs in parallel and a single spring perpendicularly thereto.
U.S. Pat. No. 2,932,482 discloses an arrangement having two pairs of leaf springs arranged orthogonally with regard to each other for allowing translational, but not rotational movement of two objects relative to each other.